Artificial satellite with an orbit having a long staying time in a zenith direction, an orbit control method and a communication system therewith

A system and method for a group of artificial satellites. The artificial satellite is placed into an orbit in which an individual satellite orbits on an elliptical orbit so that at least one of the artificial satellites is always viewable within a pre-defined range of operational elevational angle in a zenith direction from a service area. The group of the artificial satellites are satellites on respective different orbits obtained by combining an inclination angle and an eccentricity squared of the elliptical orbit so that a time period during which one artificial satellite of the group of artificial satellites is viewable from ground is substantially identical to a time period during which another artificial satellite of the group of the artificial satellites is viewable from ground.